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Monday, September 24, 2007

Scientists warn against biofuel emissions

Scientists warn against biofuel emissions

So-called biofuels made from corn and rapeseed produce more greenhouse gas emissions than the fossil fuels they are meant to replace, say British scientists.

Fuel from rapeseed used in Europe was found to produce as much as 70 percent more greenhouse gas emissions, while fuel from corn used in the United States produced as much as 50 percent more, said the study from the International Panel on Climate Change, The Times of London reported Saturday.

The findings highlight the importance of thoroughly testing alternative fuels before hailing them as solutions to global warming, said Keith Smith, an author of the report and scientist at the University of Edinburgh.

"One wants rational decisions rather than simply jumping on the bandwagon because superficially something appears to reduce emissions," Smith said.


Biodiesel Emissions Compared to Other Fuels
Fuel Types

In the table below, we give the emission characteristics of various fuels as compared to diesel. The numbers in the table reflect the percent difference for a vehicle traveling for a mile on that fuel as compared to a comparable vehicle traveling for a mile on diesel. The emissions are calculated using the Argonne National Laboratory's GREET Model version 1.5a. This calculates the emissions of various gases for the entire fuel cycle. This includes the gathering of feedstock, fuel production, and tailpipe emissions. This type of complete analysis is often referred to as a well-to-wheel or fuel-cycle analysis.

While a rough comparison of fuel types can be made, it is important to realize that these numbers can vary significantly from vehicle to vehicle. Therefore, any such numbers must be treated as a rough indication of a fuel's emissions. For this reason, all numbers have been rounded to the nearest 5%. The fuels are ranked in order of most to least greenhouse gas emissions - the emissions that cause global warming. The electric category is for a battery- powered vehicle running off of the New England power grid. The hybrid is a diesel/electric hybrid.

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